Abstract : The author performed a theoretical investigation of various means of producing optical switching. All optical switching via the Kerr effect was studied and numerical estimates for specific simple (simple here is meant to exclude four wave mixing (FWM). These estimates show that, at least for the simple devices considered, all optical switching is impractical for Naval platform use with present day materials. This may change quickly, however, due to new and rapid advances in the production of highly non-linear Kerr-like materials. Another avenue of approach to all optical switching under investigation consisted of the use of FWM. A theoretical study of the Green's functions with the appropriate boundary conditions was made and it was found that optical switching could be performed by suitable control of the pump beams. Again, however, it appears that with present day materials, this procedure is too immature for Navy use. Some details and results of these calculations may be found in the earlier quarterly reports. Other investigations include the study of transient second harmonic generation, three wave mixing theory, and simple solutions of the Master equation derived from the statistical properties of photons.